Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and closed-world scope, so the safety profile is covered structurally. Beyond that, the description contributes nothing — no return shape, no required identifiers, no cost or rate behavior — only the operation ID and a note that describe_operation carries the real schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.